I want to install a fuel pressure gauge right beneath the radio where I keep my spare change. It's just an empty box for the 6mt. I can get ignition power and a good ground, but I need a source for the lighted gauge. The source has to come on when my headlights are on. I was thinking of using the hazard button. I does light up when I turn on my lights, but I can't figure out which wire is for the light. There are four wires and I think I can indentify two. Can someone tell me which wire is for the light or even a better light source that doesn't involve me tearing up my console to find it?